The invention pertains to a sheet guide device for machines that process sheets of printing material, having a guide element which has a supporting face inclined transversely with respect to the transport direction of the sheets of printing material for side edges of the sheets of printing material, and which is mounted such that it can be adjusted by means of an adjusting device, according to the preamble of claim 1.
Such sheet guide devices, on which the sheets rest with their side edges and thus along a contact line rather than with their faces, are advantageous for the smearfree guidance of stiff sheets.
The guide elements of sheet guide devices of this type can be fixed to cylinders that transport the sheets, corotating with the latter, as is the case in the sheet guide devices described in German published patent application DE 725 705 and in German patent DE 41 11 262 C2, or can be arranged adjacent to the cylinders, as is provided in the sheet guide devices described in German published patent applications DE 258 400 A1 and DE 44 43 493 A1.
The drawback with the sheet guide devices described in the aforementioned printed documents is that changing their format has to be carried out manually by the operator. If, for example, each printing unit of a modern sheet-fed rotary printing machine comprising ten or more printing units is equipped with such a sheet guide device, and each sheet transport device arranged between the printing units is likewise equipped with such a sheet guide device, the result is a large number of operating locations at which the operator has to adjust the guide elements one after another, which results in intolerably high changeover times of the machine.
Furthermore, German published patent application DE 42 09 006 A1 describes a sheet guide device which does not correspond to the above-mentioned generic type, whose guide elements can be adjusted by a motor and are constructed as elements that contact the sheet surface, such as suction rings.
By means of such guide elements, the smearfree transport of the sheets is not ensured under all conditions and, in particular, not when stiff sheets are being printed.
The object of the invention is to provide a sheet-guide device for machines processing printing material which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which, on the one hand, ensures smearfree sheet guidance and, on the other hand, short changeover times.
With the above and other objects in view there is provided, in accordance with the invention, a sheet guide device for a sheet-processing machine in which sheets of printing material are transported along a sheet transport direction. The sheet guide device comprises:
an adjustably mounted guide element formed with a supporting face inclined transversely with respect to the transport direction for supporting side edges of the sheets; and
an adjusting device operatively connected with the guide element and comprising a motor for adjusting the guide element.
A sheet guide device constructed in this way is advantageous with regard to automating changing the format of the machine. Changing the format can be carried out after the operator has pressed a knob or after another operating command on an electronic control device linked in control terms to the remotely controllable motor by means of appropriate activation of the motor, which has a drive connection to the guide element in order to displace it, automatically by the control device without the operator having to do anything further. At the same time, print-job-specific data, such as the format width or the side marker position, which have already been input into the control device and stored in the latter, can be processed further in order to activate the motor on the basis of the format.
Provision can be made for the motor to adjust a number of guide elements at the same time, to which the motor has a drive connection via a gear mechanism. Likewise, provision can also be made for a number of motors each having a drive connection to a guide element to have a control link to the control device. Following the operating command, parallel activation of these synchronized motors can be carried out by the control device, for example integrated into a central control desk of the machine, so that the guide elements can be adjusted simultaneously into their positions required for the sheet format width to be set.
In this way, all the guide elements of a machine comprising many printing units can have their format set at once.
In accordance with an added feature of the invention, which is advantageous with regard to the precise fine adjustment of the guide element position in relation to the side edge, a screw mechanism belonging to the adjusting device and via which the motor drives the guide element in order to adjust it is arranged between the motor and the guide element.
In accordance with a further embodiment, which is advantageous with regard to the stable and anti-tilt mounting of the guide element by means of the adjusting device, a threaded spindle belonging to the screw mechanism and a threaded spindle of a further screw mechanism which belongs to the adjusting device and provides a drive connection between the motor and the guide element are mounted axially parallel to each other.
In a further embodiment which is advantageous with regard to an arrangement of the motor axially parallel to the screw mechanism, a flexible drive mechanism, via which the motor drives the screw mechanism in rotation in order to adjust the guide element, is arranged in the drive train between the motor and the screw mechanism.
In a further embodiment which is advantageous with regard to the secure support of the side edges, the supporting face extends convexly and/or concavely in its direction of inclination.
In accordance with an additional feature of the invention, which is advantageous with regard to the lightweight construction of the guide element, the latter consists of a number of supports constructed alongside one another, which together determine the supporting face, which is interrupted at points between the supports.
In a further embodiment which is advantageous with regard to supporting the sheet on both sides by means of motor-adjustable guide elements, the sheet guide device comprises, in addition to the guide element as the first guide element, a second guide element whose supporting face is arranged opposite that of the first guide element and is inclined in mirror-symmetric fashion with respect to the supporting face of the first guide element.
In a further embodiment which is advantageous with regard to the guidance of the sheet in the region of the center of its sheet format width, the first and second guide elements are assigned a third guide element, which is arranged to guide the sheet of printing material in the region between its side edges. If the first guide element and the second guide element, in order to support a sheet, are assigned to a cylinder transporting the sheet and, for example, are fitted to this cylinder, the third guide element, for example in the form of a guide bow, can be fitted to the cylinder and co-rotate with the latter. If the third guide element fitted to the cylinder and co-rotating with the latter is constructed as a blowing device, for example a blowing pipe or a metal sheet provided with blowing openings, a producer of compressed air, for example a blower, can be arranged in the cylinder or external to the cylinder and be connected to the blowing device via a rotary inlet.
In accordance with another feature of the invention, which is advantageous with regard to pneumatically supported sheet guidance, a third guide element can have compressed air applied to it and can be provided with air nozzles directed onto the sheet. Provision can likewise be made for the third guide element to be assigned a blowing device, different from the third guide element, with blowing nozzles directed onto the sheet.
In a further embodiment which is advantageous with regard to the optional adjustment of the sheet guide device either to lightweight and flexible paper sheets to be processed or to heavy and stiff sheets of board to be processed, the distance between the third guide element and a sheet transport device transporting the sheets of printing material past the third guide element can be adjusted by means of a further adjusting device, which comprises a motor for adjusting the third guide element.
In a further embodiment which is advantageous with regard to guiding the sheet as it is being transferred from one cylinder to another cylinder, the first guide element is fixed to the cylinder transferring the sheet, for example a transfer drum or a so-called guide drum, and co-rotates with the latter.
In accordance with again another feature of the invention, which is advantageous with regard to transporting the sheets of printing material by means of a sheet transport device circulating at high speed, for example an impression cylinder, the first guide element is arranged separately from the sheet transport device, immediately adjacent to the latter, and prevents the trailing edge of the sheet, which is held on the sheet transport device at its leading edge, lifting too far off the sheet transport device under the action of centrifugal force.
In accordance with a concomitant feature of the invention, which is advantageous with regard to the remotely controlled setting of the sheet guide device at both side edges of the sheet to the format width of the latter, the first guide element and the second guide element are assigned one and the same motor for driving the guide elements, or the first guide element is assigned a first motor and the second guide element is assigned a second motor. In the event that a motor is assigned to each of the two guide elements, it is possible for an asymmetrical relative position of the sheet of printing material in relation to the center of the machine and transversely with respect to the sheet transport direction to be set particularly simply.
The machine that processes sheets of printing material and which comprises the sheet guide device is preferably a sheet-fed rotary printing machine and may also be a machine that processes the sheets of printing material after they have been printed.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a sheet guide device for machines that process sheets of printing material, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.